Tectonic control on fluid flow

At depth, the circulation of hydrothermal fluids is mostly controlled by fracture networks, a consequence of the tectonic regime affecting the areas under study. Therefore, as fluids in the reservoir and the fluid pathways play a major role in the definition of the exploitability of a reservoir, GEMex will investigate the tectonic control on the fluid flow as well as the fluids themselves.

1. First, we will gain knowledge from exhumed systems in the NE of Acoculco and NW of Los Humeros areas, that are considered a Pleistocene-Holocene analogue of the presently active Acoculco and Los Humeros systems. In fact, since industrial targets are at depth, we will study the Past (i.e. exhumed systems) in order to better understand the Present (i.e. active systems). Fluids having circulated in the Past, will be studied through the analysis of fluid inclusions in hydrothermal minerals.
2. Second, relationships between brittle structures and fluid flow in the active system will be analysed. Structural features, such as fault zones or caldera faults will be mapped. This will be combined with information on porosity and permeability variations from laboratories and observations from geothermal surface manifestations to, finally, draw conclusions on the relationships between geological structures and fluid pathways.
3. Third, we will characterise the geochemistry of cold and thermal fluids and determine their origin. Fluids from boreholes and the surface will be sampled and analysed. Additionally, we will investigate the degassing processes at the surface. Soil gas measurements and tracer test will complete these investigations.